For a heat pump dryer or washer-dryer in the related art, a flock filter unit in a heat pump mounting box thereof includes an air guide structure and a flock filter mesh. However, due to a drawable design of the air guide structure, the sealability of connections between the flock filter unit and a drying air inlet and between the flock filter unit and a drying air outlet of a two-device mounting chamber is poor, such that drying air loss is caused and the lost drying air will form condensate water in the flock filter unit; moreover, the flock filter unit is not easy to clean since it is fixed on the air guide structure, thereby resulting in a serious flock accumulation phenomenon.